Czech O2 Arena upgrades with Nexo stadium audio system30 October 2014
The O2 Arena in Prague is the latest large-format multipurpose venue to install GEO S12-ST sound reinforcement systems by Nexo. The GEO S12-ST is a high-output long-throw loudspeaker developed specially for stadium and arena use.
Built for the 2004 Men’s World Ice Hockey Championships, the O2 Arena is home to the Slavia Praha and Lev Praha ice hockey teams, and also hosts a range of other sporting and corporate events and concerts. (For an update on The O2 in London, which opened in the old Millennium Dome three years after the Prague arena, and its new Brooklyn Bowl multipurpose facility, read David Davies’ feature here.)
The venue needed to replace its 10-year-old existing PA system, which was, by the venue’s own admission, under-specified and under-powered. The brief required a complete new PA/VA system to provide information and emergency announcements and music, integrate easily into the arena’s existing systems and represent good value for money.
“We looked at the best technology around the world,” says Jan Plihal, head of media technology at the O2 Arena, who chose a Nexo system with a total of 72 GEO S12-ST specialist long-throw cabinets and 24 RS18 subs.
Supplied and installed by Nexo’s Czech distributor, MusicData, the GEO S12-ST cabinets are flown from a central ‘cube’, carrying large screens on each side, which descends from the ceiling for sporting, congresses and corporate events. When the cube is lowered it is still 24m from cabinet to the floor, and Nexo says this is where the GEO S12-ST’s long-throw capability comes into its own. The compact two-way ST cabinets have been developed from the standard GEO S12 design, offering the high SPL and enhanced speech intelligibility required for stadium and arena applications.
The 24 RS18 subs – also flown – enhance events like motorsports, BMX championships and the Davis and Federation Cup tennis matches. “These days, events like this are more and more a show,” says Plihal. “It’s not just about the sports, we have to think about commercials as well.” Although a typical level for an ice hockey match is 90–94dBA, an SPL of 106dBA is possible in the arena. The system is driven by 16 NXAMP4x4 TDControllers situated in rack cases in the roof, providing 256kW of power.
The O2 Arena has also installed a new fibre-optic cabling infrastructure to carry an EtherSound ring network for the audio. Auvitran network devices deliver the signal from control room to racks with full double redundancy, while an option to switch to analogue offers even more backup. If any amplifier should fail, the system will automatically switch to another one.
As the arena staff require a degree of control over every element of the system, MusicData sat down with Plihal (pictured, right, with Music Data’s Tomas Ourednicek) to design a custom network interface which runs on iPads connected to wi-fi. This displays visual information required for day-to-day operation, such as the ability to switch on and off each of the arena’s 24 different zones set over three levels, including the pitch. The interface also displays the voltage on the output of the amps, giving a complete visualisation of the signal travelling through the system.
“We have one of the best arena acoustics, with a reverb time of less than two seconds,” he says. “The Nexo cabinets have been positioned to minimise the small reverberation problems we get from the glass-fronted VIP boxes. We expect excellent audio for speech and music, and the implementation of the emergency system is the most important thing.”